2000 Johnson 70HP Bogging and Stalling

edwardmtinney · Nov 19, 2009

My 2000 Johnson is bogging and stalling out all the time. It tends to struggle starting up if it hasn't been used in a while, but runs fine for a few minutes at idle speed. The more I use it, the better it behaves. However, it eventually starts to bog and shutter and maxes out at about 2-3 knots at 3500rpm when in gear at wot. It has recently started to stall and REALLY struggles to start back up. The strange thing is that it usually can rev all the way up in neutral, even while its bogging. Also, it seems to be worse when in choppy seas, but could just be a coincidence. It also has gotten worse over time. I just recently got the gas tank cleaned out, which contained water, and it worked for a couple days before going back to the same problems. Any suggestions?

CharlieB · Nov 19, 2009

Re: 2000 Johnson 70HP Bogging and Stalling

I suspect that some of that water in the tank has already found its way into your carbs.

Either a dirty carb or weak ignition will bag on acceleration, limit WOT speed and yet rev like crazy while in Neutral.

First thing is to install a water separating filter between the tank and the motor to prevent any further contamination of the carbs.

Flush the line to the motor then with the motor trimmed level, drain each carbone at a time, using the bowl drain screw/plug, pump the primer a few times to fllush out any water, then move on to the next carb.

While you are there at the carbs it never hurts to open the throttle and look down each carb throat as you gently squeeze the primer, watch for ANY fuel flooding into any carb. If so, then it is time to rebuild your carbs with new kits.

tashasdaddy · Nov 19, 2009

Re: 2000 Johnson 70HP Bogging and Stalling

Charlie has a good idea. but these are usually used with built in fuel tanks. not 6 gallon tanks.

the first step is to trouble shoot the motor. compression check all cylinders, spark check all cylinders. my real response is after doing this, and all is normal. a carb cleaning, with rebuild kits are in order.

directions here, and other good info. http://forums.iboats.com/showthread.php?t=299680

edwardmtinney · Nov 19, 2009

Re: 2000 Johnson 70HP Bogging and Stalling

Thanks for the suggestions guys. It is a built-in tank so I will check on those things. I don't think I have the expertise to do it myself, but I at least know what to suggest. Thanks.

edwardmtinney · Jan 28, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

Well my mechanic refuses to believe that it is a carb issue. A new coil and powerpack and $700 later it still doesn't work. Shouldn't that rule out electrical issues?

trendsetter240 · Jan 28, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

edwardmtinney said:
Well my mechanic refuses to believe that it is a carb issue. A new coil and powerpack and $700 later it still doesn't work. Shouldn't that rule out electrical issues?

All that rules out is your mechanic. He threw parts at the problem, at your expense and now you are no better off than when you started.

Do you know if the mechanic did any of the items mentioned by tashasdaddy in his post above? You need to find out if the motor has good compression in all cylinders, has good spark in all cylinders and that the proper amount of fuel is making it through each carbureter.

A simple diagnostic test you try yourself is to pump the primer bulb on the fuel line while the engine is bogging. If it picks up speed then you may have a problem with the fuel pump and or a restriction in the fule line/primer bulb.

If it doesn't pick up speed you need to follow the steps outlined by tashasdaddy and charlie B above. If you feel it's too difficult for you, take it step by step and post lots of questions on this forum. Lots of knowledgeable people here to help.

good luck!

CharlieB · Jan 28, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

Ouch!

Search iBoats forums for Joe Reeve's 'How to build a Spark Tester', it's a well written, easy to follow directions on how to build your own spark gap tester to test the ignition system. I you get a good hot spark on all cyl's then the ignition system is most likely fine.

Also search these threads for 'City of Hibbing', their on-line library has most outboard service manual available in .pdf format, find your motor, download and study the manual, clean and adjust your carbs.

edwardmtinney · Jan 28, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

I might try to give it a whirl myself since I have now had my boat in the shop four times to no avail. However, does anyone know of a good mechanic in the Upper Florida Keys? Just in case.

edwardmtinney · Jan 30, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

As it turns out, the engine was dropping a cylinder. That's why he thinks it's electrical. A fuel issue would affect all cylinders right? Does this rule out the possibility of fuel restriction?

bktheking · Jan 30, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

edwardmtinney said:
As it turns out, the engine was dropping a cylinder. That's why he thinks it's electrical. A fuel issue would affect all cylinders right? Does this rule out the possibility of fuel restriction?

Not necessarily, your motor has 3 carbs on it, one carb not providing fuel properly to the cylinder can cause it to "drop out" and eventually mess up that piston (lack of lubrication) , by dropping out is it losing spark or just not igniting an air/fuel mixture because it's not getting fuel to that cylinder?

edwardmtinney · Jan 30, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

I believe the spark test turned out ok. He moved the new coil along to the next cylinder and apparently that has helped. Haven't really heard anything from him yet though.

OzzieOzzieOzzie · May 2, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

How did you get on? Is the problem fixed?

bigbugin · May 4, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

Hey man I had the same exact problem with my 2002 90hp Johnson. It would run great in neutral but die in gear or wen I would give it throttle.and it was a s.o.b. To start..sometimes...i also did the same possible solution corrections. I put new fuel lines..water fuel sep..drained the tank..changed the plugs..everything you did and more. After hours of frustration and hundreds of dollars later..my mechanical found that one of my carbs wasn't getting enough fuel and was full of varnish...so the motor would run great without a load but as soon as it wen in gear it wouldn't have enough fuel..I ended up getting all of them rebuilt and its run flawlessly ever since. I'm a rookie to boating as well and maybe I shouldn't be giving advice, but I honestly was in the same situation so I thought I'd try and help ya out cuz we basically have the same motor.

whofan · May 4, 2010

Re: 2000 Johnson 70HP Bogging and Stalling

May sound stupid but did you try a can of seafoam through it?

I have this very same motor. My motor would keep stalling. Ran Seafoam in and it was like brand new again.

You may need a carb cleaning.

Try seafoam first.

2000 Johnson 70HP Bogging and Stalling

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